{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-89501", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.715Z", "datePublished": "2026-09-11T19:43:50.063Z", "dateUpdated": "2026-10-19T08:47:52.839Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:47:52.839Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nring-buffer: Hold cpu_buffer::lock when resizing a subbuf\n\nBecause, ring_buffer_subbuf_order_set() can clear cpu_buffer->free_page,\nhold cpu_buffer->lock to prevent races with\nring_buffer_alloc_read_page() and ring_buffer_free_read_page()." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The bug is reached only via local tracefs syscalls: write() to buffer_subbuf_size_kb (ring_buffer_subbuf_order_set) racing with read()/close() on per_cpu/*/trace_pipe_raw (ring_buffer_alloc_read_page and ring_buffer_free_read_page). No network, adjacent-radio, or physical path reaches this free_page steal.\nAC:L - The attacker controls both sides of the race: one thread toggles buffer_subbuf_size_kb to copy and NULL cpu_buffer->free_page without cpu_buffer->lock, while another reads or closes trace_pipe_raw, which takes or caches that page under the lock. Success does not depend on an uninfluenced victim state.\nPR:L - tracing_check_open_get_tr() enforces only LOCKDOWN_TRACEFS and DAC with no capable() check. buffer_subbuf_size_kb and trace_pipe_raw are mode 0640 and are routinely delegated via tracefs gid=/mode= to tracing-group members on Android/Perfetto, ChromeOS, and developer kernels, matching prior CNA tracefs UAF scores.\nUI:N - Exploitation uses the attacker’s own tracefs file descriptors and threads (open/read/close trace_pipe_raw while writing buffer_subbuf_size_kb). No separate victim mount, click, or configuration action is required.\nS:U - The use-after-free and double-free corrupt kernel ring-buffer pages and metadata within the same OS security authority. This enables local privilege escalation but does not cross VM, IOMMU, container-hypervisor, or hardware trust boundaries.\nC:H - ring_buffer_subbuf_order_set() can free the cached free_page after alloc_read_page has already claimed it, including after ring_buffer_read_page swaps it into the live reader page. Recycled heap contents are then copied to userspace via tracing_buffers_read, giving a high-impact disclosure primitive.\nI:H - The same race double-frees the page or installs a freed page as the live ring-buffer reader page, so later tracing writes and free_read_page hit attacker-reclaimable heap. This UAF/double-free is exploitable for arbitrary kernel writes and control-flow hijack, not merely a crash.\nA:H - Concurrent free of a still-in-use reader or spare page corrupts ring-buffer lists and causes kernel oops/panic on UAF or double-free. The attacker can retrigger the race at will through repeated subbuf resizes and raw-buffer reads." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/trace/ring_buffer.c" ], "versions": [ { "version": "8e7b58c27b3c567316a51079b375b846f9223bba", "lessThan": "8a496aaa3da6e8d545896c2370c7e617cc931ae2", "status": "affected", "versionType": "git" }, { "version": "8e7b58c27b3c567316a51079b375b846f9223bba", "lessThan": "6fcb0b745a0b80df62eae4a93ce52a2d061f4ac2", "status": "affected", "versionType": "git" }, { "version": "8e7b58c27b3c567316a51079b375b846f9223bba", "lessThan": "bf242baf58de03467f226c8e29554c9495dca7fc", "status": "affected", "versionType": "git" }, { "version": "8e7b58c27b3c567316a51079b375b846f9223bba", "lessThan": "24974bd0da1b47fd56c975533ead50abf754e74d", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "kernel/trace/ring_buffer.c" ], "versions": [ { "version": "6.8", "status": "affected" }, { "version": "0", "lessThan": "6.8", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.109", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.12.109" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.8", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/8a496aaa3da6e8d545896c2370c7e617cc931ae2" }, { "url": "https://git.kernel.org/stable/c/6fcb0b745a0b80df62eae4a93ce52a2d061f4ac2" }, { "url": "https://git.kernel.org/stable/c/bf242baf58de03467f226c8e29554c9495dca7fc" }, { "url": "https://git.kernel.org/stable/c/24974bd0da1b47fd56c975533ead50abf754e74d" } ], "title": "ring-buffer: Hold cpu_buffer::lock when resizing a subbuf", "x_generator": { "engine": "bippy-1.2.0" } } } }